Listening to the Stars/Nov2008
From I2U2
Happy Thanksgiving! Welcome to Listening to the Stars, LIGO Hanford Observatory's electronic newsletter. Please reach us through the contacts below if you need additional information on items from this edition.
Contents |
[edit] What's New at LIGO Hanford?
Visitors to the Observatory will notice a striking display in the lobby area of our office and auditorium building -- an Advanced LIGO Controls Prototype Quadruple Suspension. This roughly 1000-pound steel mouthful consists of four vertical layers of masses. Each mass is attached to the mass above it by suspension wires, hence the name "quadruple suspension." In simple terms, the suspension is a four-level pendulum. Actually, it is a pair of four-level pendulums that are suspended side-by-side; the 'main chain' and the 'reaction chain.' The display apparatus is a prototype, built at Caltech and tested at MIT, which was used for development of the Advanced LIGO mirror control systems between 2006 and 2008. Interferometer mirrors will serve as the bottom pendulum masses of the main chain in the Advanced LIGO production units. Control forces to stabilize the main chain masses will be applied from the reaction chain. We empathize with those who might be thinking "I can't imagine what this looks like." Come and personally inspect the apparatus on a LIGO tour or at one of LHO's special events for the 2009 International Year of Astronomy.
Words of the Week: Brachistochrone and Tautochrone. Your copy of Webster's may not include these terms, but some readers may recognize them as curved surfaces that received the attention of luminaries such as Huygens, Galileo, the Bernoulli brothers, Newton, Leibniz, Euler and Lagrange. LIGO Hanford's newest hands-on exhibit demonstrates some of the interesting properties of curved-surface motion that these scientists/mathematicians studied as they explored the problems of the brachistochrone and tautochrone. For the benefit of our younger visitors, we've simplified the name to the "Golf Ball Racer." Our thanks go to the outreach team at the LIGO Livingston Observatory Science Education Center LIGO Livingston Observatory Science Education Center for the design of this exhibit.
In the "We've got it but you can't see it" department, LIGO is pleased to report that Output Mode Cleaners (OMC's) have now been installed inside the vacuum systems of the H1 (Hanford) and L1 (Livingston) 4-km interferometers. The OMC is a key element of the current Enhanced LIGO program that intends to double the sensitivities of H1 and L1. Each interferometer has always employed a pair of input mode cleaners, one on the laser table and another suspended inside the vacuum. These are optical cavities in which laser light of only a single mode is allowed to resonate. They act as filters to further purify the laser light that enters the interferometer. The OMC will filter the light coming out of the interferometer, removing mode impurities that the light has accrued on its long journey through the detector. Although the OMC is now hidden from view inside a chamber, LHO staff can share it with visitors via photos. Most significantly, in the LHO control room you'll be able to witness the exceedingly stable OMC output beam.
[edit] Outreach Information
The next Observatory tour will occur on Saturday, December 13 at 1:30 PM. Now that winter has arrived, participants are encouraged to bring warm clothing for the walking portion of the tour. Guests who might need walking assistance are always welcome to contact LHO in advance of a tour (509-372-8248) if special arrangements would be helpful.
LIGO congratulates Washington MESA (Mathematics, Engineering and Science Achievement) for receiving the 2007-2008 Science Education Advocacy institution award from LASER (Leadership and Assistance for Science Education Reform). LHO was fortunate to receive this award in 2006-2007. MESA works with school districts, students and families in regions across Washington to bolster students' awareness, readiness and confidence in relation to technical career paths and majors. The Tri-Cities region is served by the Valley/Tri-Cities MESA office which is located on the WSU Tri-Cities campus. Hundreds of students have visited LIGO Hanford and other regional science installations under the auspices of YV/TC MESA; field trips such as these are just one of the services that MESA delivers.
[edit] Science News of Note
Startup of the Large Hadron Collider (LHC) at Europe's CERN facility captured the public's attention this fall. On September 10, 2008, LHC personnel successfully launched beams of protons in clockwise and counterclockwise directions around the 27-km ring, bringing years of development, construction and commissioning to fruition in a remarkably smooth inaugural event. LHO visitors since then have asked a number of questions about connections between LHC research and LIGO research. Certainly there are parallels. Both sets of facilities occupy large pieces of real estate. Both projects pursue fundamental questions about the nature of energy, mass, space and time. The LHC will undertake its mission by accelerating protons to near-light speed, colliding them at enormous energies and analyzing the resulting spray of subnuclear particles and energy. It is a probe of the very small. LIGO seeks the very large -- black holes, solar-mass and heavier neutron stars, and the propagation of gravitational waves through huge expanses of space. One point of convergence between the projects relates to the nature of the early universe, when the forces that we now experience as distinct may have been unified under energy conditions that the LHC seeks to re-create.
Less than two weeks after the first beam, LHC suffered an electrical fault that resulted in damage to hardware in one of the beam sectors. Repairs will keep the beam turned off until the spring of 2009. Project personnel have expressed confidence that the accelerator will return to full operations at that time and that the project's experimental program will begin soon thereafter. This episode brought much attention to the fact that hardware failures remain a possibility in devices that are so large and complex. A circumstance more deeply felt by LIGO was the May 9, 2008 failure of a vacuum chamber viewport (window) at the Virgo gravitational wave detector in Italy, an instrument quite similar to LIGO. The viewport implosion contaminated the chamber's interior. Virgo personnel are replacing all 100 of the detector's viewports with an improved design. Fortunately these changes can occur alongside previously scheduled commissioning activities, largely preserving a schedule that will result in the next joint gravitational wave science run in 2009. LIGO has undertaken an intensive viewport evaluation since the Virgo event, including laboratory pressure testing of sample LIGO viewports.
[edit] Subscription Information
- To subscribe to "Listening to the Stars", send an email to outreach@ligo-wa.caltech.edu and include "subscribe to newsletter" on the subject line.
- To unsubscribe, send an email to outreach@ligo-wa.caltech.edu and include "unsubscribe" on the subject line.
